Top feed dog for sewing machines



C. W. MUELLER TOP FEED DOG FOR SEWING MACHINES Dec. 12, 1939'.

Original F iled May 18, 1937 Charles 14 Mueller Patented Dec. 12, 1939 UNITED STATES PATENT OFFICE TOP FEED DOG FOR SEWING MACHINES Charles W. Mueller, St. Louis, Mo., assignor to Lewis Invisible Stitch Machine Company, St. Louis, Mo., a corporation of Maine Original application May 18, 1937, Serial No.

Divided and this application March 19, 1938, Serial No. 196,970

5 Claims.

.: stitch type.

This application constitutes a division of my co-pending application SerialNo. 143,387, filed May 18, 1937, for improvements in Sewing machines.

It has been observed that when joining the edge of a superposed fabric, such as a hem fold, to a base fabric, on a blind stitch machine of the lock stitch type, the setting of the stitches results in the puckering of the base fabric on the fair side thereof.

One of the important objects of this invention lies in the provision of a top feed dog which will clamp the bobbin thread extending diagonally from the next to last formed stitch to the bobbin, against the fabric while the fabric is being fed and the needle thread is being taken up to set the stitch, whereby an increased length of bobbin thread will be laid between adjacent needle loops and a line of loose stitches will be thereby formed with the result that the puckering effect in the base fabric above noted will be avoided.

With the above and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawing.

In the drawing:

Figure 1 is an enlarged top plan view of a presser foot showing the top feed dog in dotted lines and in cooperative relation to the bobbin thread,

Figure 2 is a top perspective view of a top feed dog constructed in accordance with my invention,

Figure 3 is a perspective view of the front end of the dog without the thread clamping portion,

Figure 4 is a bottom perspective view of the feed dog, and

Figure 5 is a detail perspective view illustrating a modified form of the feed dog in which the thread clamping portion is formed integrally therewith.

Like reference numerals designate corresponding parts throughout the several figures of the drawing,

In the accompanying drawing, I have illustrated a presser foot B having a longitudinal opening 28 through which a node of fabric being hemmed is projected upwardly by a ridge forming element (not shown) into position to be entered by a needle 21 which reciprocates centrally across said opening. The needle carries a thread J and cooperating with the needle to form a line of lock stitches is a bobbin which carries a thread E.

An intermittent 4-motion feed dog is located directly in rear of the needle path, and is actu- 5.:

ated by a mechanism shown in my co-pending application referred to above. If the next to last stitches are set too tight, it will result in the puckering of the fair side of the material.

I have overcome this objection by providing a 101 feed dog I with a front section which functions to clamp the bobbin thread extending diagonally from the next-to-last formed stitch to the bobbin against the fabric during the take-up movement of the take-up lever whereby sufi'icient slack in 15 the laid bobbin thread will suffice to prevent the puckering effect above noted.

To this end, the feed dog I includes a body portion 59 having a stepped front portion forming a resultant toe 60 which projects forwardly from 20 the right hand corner thereof, a recess 6| which is located at the left hand corner of the body portion, and a front transverse wall or edge 62 which merges with said toe and recess. The upper face of the body portion is milled to form a 25 fiat horizontal bearing surface 63 and a trans-- verse shoulder 64. The under face of the body portion is provided with two longitudinally extending feed sections 65, 66 which are spaced apart by a longitudinally extending groove 67, 30 the section 65 being located on the left side of the body portion directly in rear of the recess BI, and the section 66 being located on the right hand side of the body portion and extending under the toe 60, the front end of the groove 61 5 merging with the front wall 62. A vertically yieldable thread clamping section 68 is positioned in the recess Bl and the under face 69 thereof is smooth and is normally disposed slightly below the plane of the feed sections 65, 66. The clamp- 40 ing section 68 is supported on the body portion 59 of the foot through the medium of a rearwardly extending spring arm 10 which rests on the bearing surface 63 and is secured to the body portion by a screw H, the rear edge 12 of the arm 45 abutting the shoulder 64 to retain the section against turning.

It will be observed, as shown in Fig. 1, that the section 68 of the feed dog when at the beginning of its feeding stroke, is clamping the 50 bobbin thread E, which extends diagonally from the next to last formed needle thread loop to the bobbin, against the fabric. Consequently this portion of the bobbin thread will be clamped by the feed dog during the feeding stroke thereof 55 and while the take-up lever (not shown) is moving rearwardly to take up the needle loop, the feed dog releasing the bobbin thread an instant before the lever reaches the rear end of its stroke, whereby the next to last needle thread loop will be set but without taking up the slack bobbin thread which extends between the last two formed needle loops.

In Figure 5 of the drawing, I have illustrated a modified form of the invention in which the thread clamping portion is formed integrally with the main body portion 59, as indicated at 13.

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of my invention.

I claim:

1. A top feed dog including a body portion having a feeding surface on its under face, and a thread clamping section mounted on the body portion and disposed in front of said feeding surface, and mounting means for supporting the feed dog with said thread clamping section presented for engagement downwardly in thread clamping relation with the upper surface of a fabric being sewn.

2. A top feed dog including a body portion having a feeding surface on its under face, and a vertically yieldable thread clamping section mounted on the body portion and disposed in front of said feeding surface.

3. A top feed dog including a body portion hav ing a feeding surface on its under face, and a thread clamping section mounted on the body portion and disposed in front of said feeding surface, the lower surface of the section being smooth and disposed slightly below the feeding surface, and mounting means for supporting the feed dog with said smooth surface presented downwardly for thread clamping engagement with the upper surface of a fabric being sewn.

4. A top feed dog including a body portion having a feeding surface on its under face, and a thread clamping surface disposed in front of said feeding surface, and mounting means for supporting the feed dog with said thread clamping surface presented downwardly for thread clamping engagement with the upper surface of a fabric being sewn.

5. A top feed dog including a body portion having a feeding surface on its under face, and a smooth thread clamping surface disposed in front of and in a plane lower than that occupied by said feeding surface, and mounting means for supporting the feed dog with said thread clamping surface presented downwardly for thread clamping engagement with the upper surface of a fabric being sewn.

CHARLES W. MUELLER. 

